The San Salvador Earthquake of October 10,1986—Processed Strong Motion Data

Strong-motion records were recovered from nine accelerographs at seven stations of the El Salvador Geotechnical Investigation Center Strong Motion Network following the damaging 5.4 Ms San Salvador earthquake of October 10, 1986. The sites were all within 6 km of the epicenter; peak horizontal accelerations at ground level ranged from 0.32 to 0.72 g. The duration of strong shaking was about 3 seconds at most sites. One 10-story concrete building was instrumented with recorders at the basement, second floor, and roof level. The maximum accelerations recorded at this building were 0.47 g at the basement, 0.69 g at the second floor, and 0.91 g at the roof.

Eight of the accelerograms were digitized and processed. A maximum horizontal velocity of 80 cm/s was obtained for a station 4 km from the epicenter. Peak velocity for the other stations ranged from 26 to 75 cm/s. The maximum horizontal displacements ranged from 5 to 18 cm.

The San Salvador records and spectra are compared to other close-in observations such as the Station 2 record from the ML 5.6 Parkfield earthquake of 1966. The San Salvador records share many features with the Parkfield record. In general, the peak accelerations recorded at many of the stations are larger than previously recorded values at close-in distances from earthquakes of similar magnitude.